使用開短路負載實現雙頻雙零階共振天線

Abstract

本篇論文基於複合式左右手材料(composite right/left-handed transmission line，CRLH)的零階共振天線(Zeroth-Order Resonant Antenna，ZOR antenna) 提出變形應用，使之達到雙零階共振之特性，一般零階共振天線採用零階與負一階共振使之達到雙頻，而本論文在設定目標頻率1.8GHz和2.4GHz兩個頻率下，同時做到零階之共振而有雙頻的效果。

此天線之設計流程從調整指叉電容與串聯電感達到1.8GHz串聯共振、並聯電感達到2.4GHz的並聯共振。然後設計一個會隨頻率改變阻抗之負載使其阻抗達到1.8GHz開路及2.4GHz短路，此負載加在天線本體後端，可使天線的串聯共振與並聯共振同時存在，接下來本論文提出一個雙頻匹配網路之設計以使本天線可以在1.8GHz和2.4GHz兩個頻率達到匹配。

在本篇論文之雙零階共振天線設計詳述電容電感疊接趨近合成式左右手傳輸線實作，並利用合成式平衡左右手傳輸線與零階共振理論設計開路/短路共振雙頻零階的天線(1.8GHz行動通訊頻段，2.4GHz，5GHz無線網路頻段)，並避免使用集總元件達到LC匹配到指定頻率，且在不使用Lumped元件下有效縮小天線尺寸為設計目標。

In this thesis, a dual band antenna design using dual zero-order resonance is proposed. General zeroth order resonant antenna (ZOA) using a zero-order and negative-order resonance to achieve dual band. It needs two units cell in cascade. The proposed ZOA reduces the cell number to one, which leads to the shrink of the antenna size.

The design begins with the synthesization of the zero-order resonance unit cell, which is composed of an interdigital capacitor and short stub. Then, a well-designed termination circuits is proposed to enable simultaneous excitation of the zeroth-order series and shunt resonances.

In order to validate the above concepts, a dual band ZOA is proposed. The antenna is designed that the zeroth-order series and shunt resonance are located at 1.8 GHz and 2.4 GHz. The termination circuit is realized by an inductor series with a parallel LC tank that its impedance is open at 1.8 GHz and short at 2.4 GHz. When the termination circuit is used, the antenna can resonate at the designed 1.8 GHz and 2.4 GHz. Finally, a dual band matching circuit is proposed to match the antenna to a 50Ω terminal.

This antenna avoids the use of lumped element and multiple unit cells, which leads to further cost reduction of the ZOA.